Hello! I am hoping you can help me. I have two small garden plots on the...

Asked June 30, 2016, 12:47 PM EDT

Hello! I am hoping you can help me. I have two small garden plots on the south side of my house in Richfield, MN; they are separated by a concrete step that leads to my side door. I have lived here for 19 years and I bought the home from my grandparents, who were the original owners. This spring, most of the plants on the east side plot did not bloom (see image #1). The peony bush did bloom; however, the past several years, it has developed a "fungus" (??? my diagnosis - white stuff on the leaves) and it is starting down that path again, with some of the leaves becoming discolored (see image #2). I was told that this may impact all of the plants.... Anyhow, the coral bells next to the peony bush are very small and are not producing flowers; the coral bells farther away (and on the other side of the cement step) are fine. The plot had been filled with Echinacea, and they did so well. I am especially sad because some of the Echinacea was from my sister's garden, who has passed. The plants on the other side of the cement step are fine.... (see image #3). What do you suppose is going on and what can I do? Thank you so much for your help! Susan Lavell

Hennepin County Minnesota plant disease identification horticulture

1 Response

Re: powdery mildew - The peony likely has powdery mildew, a very common fungus in our gardens. Older varieties of plants like peonies, Monarda (bee balm), roses and some other plants are susceptible. Some newer cultivars are bred to be resistant. Squash family members are also susceptible. Because it is so common, it is difficult to eradicate. Fortunately, powdery mildew is more cosmetic damage and not fatal to amn other wide healthy plant. If branches become covered in the mildew, cut them off and dispose of them. Here's a publication on powdery mildew that tells more: http://www.extension.umn.edu/garden/yard-garden/flowers/powdery-mildew-on-ornamental-plants/

Re: why plants are not growing well on one side of your steps and yet grow well on the other, this could be due to a few reasons:

  • Soil health: the soil could be poor quality and / or have poor drainage on the east side. A soil test will help you determine what amendments (fertilizer, compost, etc.) should be added. You may want to submit two separate tests – one for each side – and see how they compare. Instructions are found here: http://soiltest.cfans.umn.edu/
  • Water & drainage – In image #1 I see a window well covered on the east side and no plants there. It makes me ask if you have rain that flows of the roof there (hence the cover), then off the cover and into the soil. Excess water combined with possibly poor drainage could very well be rotting the plants you tried to grow. Echinacea prefer well-drained soil, so perhaps they lived for a short time. Coral bells have plant crowns at the soil surface and require good drainage well. In addition, there are some cultivars of Echinacea and coral bells available on the market that are not reliably hardy in Minnesota.
  • Have you had construction work done there to fix / maintain that window well? It could be likely that the soil is compacted 6-8 down and the plant roots cannot grow any deeper. This could be why they do well for a short time and then die.